You need to devide 205 by the number of gallons you put in the tank. As hcmq said, when the fuel light comes on you have around 3-5 gallons left.

205/20 = 10.25 which isnt bad for 4 mile trips.

I get about 14.5-15.5 MPG with solid highway driving, and about 12 MPG in city driving (although city driving for me is usually longer than just 4 miles).

I think once you get your speedo adjusted you should see between .5 to 1 MPG increase (depending on which tires yours had stock), and that would be where I would expect your truck to be at.

 

Awsome, yeah I was factoring for about 2-3 gallons left in the tank, wasnt aware there was 5. I guess ill get the speedo adjusted. I had 255/65's on before I put the 265/75/16's on. I'll call around and find out how much it costs to adjust it.

 

I've got a 2002 XTR 4x4 with the 5.4 and my latest mileage check was 19.9 (mostly hwy with some city).Hwy mileage was 120 kmh (75 mph).Only thing not stock is a K&N filter.

 

I can only wait for winter to hit up here and drive this thing in 4x4. LOL, oh well I beleive im going to take it in for a tune up and oil change before the snow falls.

 

I fill the tank up until the pump "clicks" off, reset the trip odometer. When I need gas again, I fill it the same way and take the number of miles driven and divide that by the number of gallons of gas it took to fill it. I have only ran the tank down to the point of having my fuel light come on once, and I believe that I had around 330 miles or so on it.

Regarding any tune ups etc., I just purchased it towards the end of March this year and it is a "certified" used vehicle from Ford. I have not had it in for any work except for an oil change. It is my understanding that with it being certified, any of these items/problems should have been repaired before I got it. I assume that the previous owner had the speedo recalibrated when he put the 265's on it.

Hope that this helps.

 

I have a '02 S-Cab with the 5.4 and I get about 10 to 11 mpg quite regularly. I have ever since it was new. If I baby it on the highway with no AC (read: drive the speed limit) I have gotten as high as 19 mpg. If I slug it hard + AC, I have gotten as low as 8mpg. I check the mileage at every fill up.

 

Well, do you guys know that if I get the superchip if it will change my speedo and adjust for my tire size? Or is this something that has to be done manually? If I could just get a chip ill hold out and get one of them.

 

With my 2000 4x4 SCab 5.4 / 3.55, I get 15.4 mpg with a K&N drop in, SuperChips 1715 set for Tow Perf, AMSOIL 5W-30 and running 93 octane. I drive a even mix of city and highway miles as it is 35 mile to my work. Don't know how much of an impact, but I also leave my tailgate down - on the interstate I run about 70 mph.

I use a fuel log book and caculate my mileage every fill up, right now it's dropping off a little - about time for an oil change.

When I first got the truck (bought used with 84k - now at 96k) I was getting about 12.3 mpg - so some of this stuff improved the MPG.

I also tow a 5500 lb camper and when towing I get any where between 9-12 mpg depending on my speed and topography of the route.

One easy way to check the accuracy of your spedo is to travel down a highway that has mile markers - then sert your speed to exactly 60 mph and as you pass one marker use a stop watch and you should hit the next marker at one minute (60 mph = 1 mile/min).

I agree with other here - try a tune up and oil change. One other thing is to disconnect the neg post of the battery to reset the PCM, this should make the computer recalibrate to teh current conditions of the truck. I do this anytime I clean the throttle body or air filter.

 

Seeing as how the dual exhaust / intake have been on for about a month now, the PCM should have allready recognized the changes. As stated above I just did an oil change on it less than 1,000 miles ago. So, wonder if the chip is the next step and set it up for the tires and what not.

 

I have a 99 supercab with the 4.6, w/ dual exhaust. I usually get around 12-15 where i live. Farthest i drive is 10 miles before i have to stop. Usually 4 miles. So alot of stop and go. I usually get on it more to hear it rumble. I will even get 12.5 pulling our 21 foot boat out of overdrive at 60 mph on a trip. Nothign to complain about there....But last weekend i got 17.5 driving on a long trip pulling nothing. I drove easy and i had 390 miles on my tank something ive never done before. I was in a good mood

 

Yeah, im thinkin my speedo is messed up. I know if I go on a drive on the highway I can get 100 miles on a 1/4 tank without a problem. So im thinkin I just need to get a chip and set things straight.

 

4x4,
You stated that you assumed the last person set the speedo to corrected values! (we all know what "assume" breaks down to mean) All kidding aside check the door codes for tire size and axle ratio's and if they match what you are now running then the trucks speedo should be factory right. Not to mean that it's correct, but programed as ford thought was correct. (all tires the same size are not the same size)

The Super chips micro tuner 1715 for one, does allow you to make program changes for axle ratio's and tire size. The step for tire size can be a bit confussing. The microtuner ask for an input of your tires diameter (this is were the problem starts) do you measure the dia. with the tire on the ground and the vehicle weight on it, or off the truck, or deflated, or what ever!!!!!!!!!!!
I played the game and measured it on the truck, thinking that is were it runs on the highway...da. Well my 31" Goodyears measured 31.25(hard to tell were the top is with the tape held out to the side of tire) so I set the microtuner for that and still the stopwatch and 1/4 mile marks on the interstate (the state patrol have them marked for the airplane on I-80 here in Iowa) tell me I'm still off. So..........I tried this, put a peace of tape on the side wall at ground level and marked the ground, then drove forward one exact revolution and measured the distance and dividied by pi (approx 3.1417 for those of us that's been out of school for awhile) and came up with 30.68" so I set the 1715 for 30.75 (it only lets you do 1/4" increments) Now my speedo is dead on.

Boy is this guy windy or what!!!!

The only way to check milage is to take the "true mile driven" and divide by the gallons pumped. Not what the gas guage says at half full.

Hope my trial and errors will be helpful!

Gene

PS I just thought I was done. My Technical Specifications for a 2000 F150 shows that for a 7700 payload group a choice of P255/70R16 or LT245/75R16 thats 695 and 679 revs per mile@45mph respectivily.
My truck uses P265/70R17 with the off road package and turns 654 revs per mile@45mph.
Thats a big difference in what the pcm has to be programed for the three different tire sizes. Just food for thought!

What pcm code is on your door post (inside on hinge side of passengers door). Mine's uat3. I bet yours is different, being you have 3.73 gears?

 

I have a 98 4X4 Xcab that had a 4.6 in it. I swapped it with a 2001 5.4. I have Magnaflow cat back, K&N FIPK, and a Superchip. I'm running 3.73 gears with 265/75 tires and I get 280 - 300 miles per tank. It usually comes out to be 14-15 mpg.

I think I'd take it in. You should not be getting that low of mileage.

Good luck!

 

98 f150, 5.4L 17" rims,gears???

I frequently hit 300-330 miles per tank, 300 if I have my 2 kayaks strapped on top@highway speeds! My best was 366@23 gallons.
15.9mpg

77,000miles!

 

Like sclime & frostby, I get 300+ out of every tank, unless I'm pulling the trailer with 6 motorcycles on it, then hang onto your behind it's 10 to 11 depending on which route I take to Daytona.

There's somthing wrong, check it out!

Gene